A method of scrubbing surfaces such as floors and pavements with a scrubbing machine wherein the same cleaning solution is recycled and reused after filtering out solid material from the recovered cleaning solution.
Experiments have been conducted with a hydrocyclone to try to clarify dirty scrub water for possible use in scrubbing machines; however, due to the fineness and low densities of the colloidal particles in the dirty scrub water, only a small fraction of the weight of the suspended particles are successively removed. As a result of the remaining particles of dirt the scrub water that outflows from the hydrocyclone is still too dirty for reuse.
In the prior art, filters, including reverse osmosis systems, have been tried in order to clarify water for recycling in a scrubbing machine. However, due to the small size of the dirt particles and large number of them in the dirty scrub water, the filters plug quickly and thus require frequent cleaning or changing. The filters must be extremely fine to remove the small particles and thus plug quickly, and require considerable power to operate. Centrifuges have also been tried for clarifying dirty scrub water for reuse in scrubbing machines, but the high cost of centrifuges and associated equipment together with high power requirements make centrifuges impractical in a scrubbing machine
The present day scrubbing process most frequently used involves providing at least two solution tanks on a scrubbing machine, one being a clean solution tank that contains clean water and detergent for scrubbing and a second being a dirty solution tank into which the recovered dirty scrub water is returned. When all the clean solution has been used for scrubbing, the machine is returned to a suitable refilling point where the dirty solution tank is emptied and the clean solution tank is filled, and thence the machine is returned to the point where the scrubbing operation is recommenced. The dirty water is usually dumped down the drain causing further problems for waste treatment facilities and causing pollution problems. It has been estimated that up to 30 to 50% of the machine use time with this type of operation is in the clean solution preparation, the emptying of the dirty solution tank and transport time back and forth from the work area to the fill and empty point. On scrubbers now in use only one half of the existing tank capacity is useful for containing cleaning solution because the other one half must be used to hold recovered dirty scrub water.
In scrubbing surfaces the fine particles of dirt become uniformly dispersed in the scrubbing solution on the surface and when the dirty water is picked up (usually with a squeegee,) the thin film of water that is left on the surface after squeegeeing also carries these fine dirt particles and when the residual water dries, a film of dirt is left on the surface, even with the most efficient squeeging system.
Frequently, it is necessary to go over the scrubbed surface a second time with clean rinse water in the clean solution tank in order to remove a part of the dirty film left on the surface after the first scrubbing operation.
In order to overcome problems such as the above, including minimizing the frequency of having to replenish the clean solution supply, reducing dumping and travel time as well as overcoming other problems, this invention has been made.